He had Ven's heart inside him also. So When he struck himself w/ the keyblade, realesed Ven's heart too, thus creating Roxas his nobody and Namine. Roxas was created based on Ventus. So Sora still had his heart from the beginning.
My vote was i thought they were equally evil. but Frieza is more badass, And if he was in Naruto Shippuden it would take a Miracle for Naruto beat him. Even if he's Sage now. lol